The present disclosure relates to a power semiconductor device.
An insulated gate bipolar transistor (IGBT) refers to a transistor having a bipolar structure as a result of manufacturing a gate using a metal oxide semiconductor (MOS) and forming a p-type collector layer on a rear surface of the transistor.
After a power metal oxide semiconductor field effect transistor (MOSFET) according to the related art was developed, the MOSFET has been used in fields requiring fast switching characteristics.
However, due to a structural limitation of the MOSFET, a bipolar transistor, a thyristor, gate turn-off thyristors (GTOs), and the like, have been used in fields requiring a high voltage.
Since the IGBT is characterized by low forward voltage loss and fast switching speed, it has been widely used for fields which are impossible to implement with the existing thyristor, bipolar transistor, metal oxide semiconductor field effect transistor (MOSFET), and the like.
Describing an operation principle of the IGBT, in the case in which an IGBT element is turned on, a higher voltage is applied to an anode thereof than to a cathode thereof, and in the case in which the voltage higher than a threshold voltage of the element is applied to a gate electrode, polarity of a surface of a p-type body region located at a lower end of the gate electrode is reversed to thereby form an n-type channel.
Electron current injected into a drift region through a channel induces an injection of a hole current from a high concentration p-type collector layer located at a lower portion of the IGBT element, similar to a base current of the bipolar transistor.
Due to a high concentration injection of the minority carriers, a conductivity modulation phenomenon occurs in which conductivity in the drift region is increased by tens to hundreds of times.
Unlike the MOSFET, since the IGBT has a highly reduced resistance component in the drift region due to conductivity modulation, it may be used at a very high voltage.
The current flowing into the cathode is divided into the electron current flowing through the channel and the hole current flowing through a junction between the p-type body and an n-type drift region.
Unlike the MOSFET, since the IGBT has a p-n-p structure between the anode and the cathode due to the structure of a substrate, it does not have a diode embedded therein, such that it needs a separate diode connected thereto in anti-parallel.
The above-mentioned IGBT has main characteristics such as maintenance of blocking voltage, a decrease in conduction loss, and an increase in switching speed.
Particularly, in order to maintain the blocking voltage, a termination region is formed around an active region in which a current flows at the time of operation of the IGBT.
Since an entire size of the power semiconductor device is limited, the active region of the power semiconductor device is decreased in the case in which the termination region is increased in the power semiconductor device, such that performance of the device may be decreased.
Thus, a method capable of decreasing the size of the termination region while sufficiently maintaining the blocking voltage of the power semiconductor device has been demanded.